The American Society for Microbiology (ASM), the largest single life science Society with approximately 40,000 members, is writing to comment on the draft guidance announced by the Food and Drug Administration (FDA) on June 29, entitled “The Judicious Use of Medically Important Antimicrobial Drugs in Food-Producing Animals.” The ASM believes the guidance, if adopted, would be a significant advance in combating the spread of microbial pathogens that have acquired resistance to one or more drugs used to treat human diseases. The ASM supports both principles recommended in the FDA document: 1) limiting medically important antimicrobial drugs to uses in food-producing animals that are considered necessary for assuring animal health, and 2) limiting such drugs to uses in food-producing animals that include veterinary oversight or consultation.

The ASM agrees with the FDA’s conclusion, based on its review of scientific evidence to date, that “using medically important antimicrobial drugs for [food animal] production purposes is not in the interest of protecting and promoting the public health.” In the United States, these drugs can be added to animal feed and water in low concentrations, thought to enhance animal growth and improve feed efficiency. Unfortunately, “subtherapeutic” or “nontherapeutic” use of antimicrobial drugs that are, or could be, effective against human and animal pathogens has been shown to result in the development of drug-resistant microorganisms in the animals. Studies have shown that these resistant organisms can then be transmitted to humans through ingestion of food or from the environment, with enhanced human morbidity, mortality, and health care costs in an era of declining discoveries of new therapeutic drugs.

For more than 50 years, antimicrobial drugs have been used in human and veterinary medicine to great benefit for public health. Yet an ever increasing number of drug-resistant microorganisms have greatly alarmed public health officials, particularly over the past decade. We have seen new patterns of drug resistance in global pathogens like malaria and tuberculosis, and domestically methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile have emerged as widespread pathogens in healthcare and community settings. One estimate suggests that between 5 and 10 percent of all hospitalized patients in this country acquire a drug-resistant infection, adding $5 billion in annual healthcare costs. Invasive infections caused by MRSA affect about 94,000 people in the US annually, contributing to 19,000 deaths.

Microbial drug resistance is driven by various factors, including the naturally occurring genetic changes that help microorganisms survive in changing environments. Multiple studies over recent years substantiate that the misuse and overuse of human and veterinary drugs also can accelerate the emergence of drug-resistant pathogens. The new FDA guidance recognizes that using medically important antimicrobials to increase food-animal production, rather than to treat specific animal diseases, can create additional evolutionary pressure selecting for drug-resistant pathogens. We agree that such therapeutics must be used judiciously in both human and animal medicine, to help preserve highly effective drugs against some of the most pervasive causes of morbidity and mortality.

The ASM has repeatedly urged that preventative actions be taken against emerging drug resistance, including expanding education programs on proper use to increasing resources for much needed basic and applied research in microbiology and related fields. The ASM supports science based evaluations of antibiotics used in agriculture. Research is also needed to understand the risks and benefits of preventative use. The ASM applauds steps already taken by government and public health officials, such as the interagency National Antimicrobial Resistance Monitoring System (NARMS) and the Centers for Disease Control and Prevention (CDC) educational campaign, Get Smart: Know When Antibiotics Work. NARMS data indicate, for example, that cephalosporin resistance among salmonella bacteria isolated from humans has increased significantly since surveillance began in 1996, and similar resistance occurs among bacteria isolated from livestock and retail meats. Genetic analyses show that in some cases the bacteria infecting humans and those found in food tied to the disease outbreak are the same, tracking movement of resistant pathogens through the food supply. Concerns over the link between drug resistance and use of antibiotics for food production have already prompted European countries to restrict or ban non-therapeutic use of various antimicrobials. Research should reveal if the Danish/European ban of antibiotics as animal growth promoters has achieved the goal of reducing resistant infections.

We believe it is importance to continue to collect, isolate, and test microorganisms for antimicrobial susceptibility as part of the comprehensive strategy to address antimicrobial resistance. We also encourage the government to help ensure new product development for the treatment of infectious diseases in food producing animals and to monitor both the positive and negative impacts of the new guidance.

The ASM supports the FDA guidance as one important step in what we believe must be a comprehensive approach to antimicrobial resistance. An effective strategy must include a coordinated effort that encompasses guidance and regulatory changes for food production and healthcare, industry incentives to create new therapeutics, research, education and improved oversight of antimicrobials in human and veterinary medicine. To succeed, an integrated strategy will require increased financial resources and strong collaborations among the many entities involved, from government agencies and pharmaceutical companies to healthcare providers, veterinarians and agricultural producers. The FDA’s draft guidance calls for voluntary compliance in restricting non therapeutic drug use in food animals, underscoring the importance of mutual agreement and cooperation among stakeholders.

We appreciate this opportunity to comment on the FDA draft guidance, and commend the agency’s efforts to protect public health against the growing problem of antimicrobial resistance.